The marketing of detergent products often involves the use of distinctive product aesthetics to help consumer differentiate one given product from another commercially available product of the same general type. Colored e.g. dyed or pigmented, speckles are sometimes used to create distinctiveness. It has been found that some consumers associate products having dyed particles with improved cleaning so that the consumer acceptance of products comprising colored particle can be higher than products not comprising such colored particles. Furthermore, the use of dyes or pigments to provide wash water with a blue colour is also known and has historically been associated with better cleaning of white fabrics. Such “blueing” of the wash water has been achieved by additives containing dyes or pigments for adding directly to the wash water in addition to the laundry detergent. Attempts have been made to incorporate coloured agents into detergent compositions, either to provide particular product aesthetics, blueing of the wash water or even to increase perceived cleaning of white fabrics. However, problems have been associated with the use of dyes or pigments directly in detergents, particularly that they can lead to spotting or staining of the fabrics being laundered.
Examples of art in this area include WO00/27980, which discloses speckle particles having a specific sparkle index and transparency index which is colored by addition of a dye pigment and/or brightener. U.S. Pat. No. 6,541,437 discloses speckled detergent compositions comprising colored glassy phosphates. U.S. Pat. No. 4,097,418 relates to agglomerate colored speckles for use with white or lightly colored detergent granules to provide detergent composition having a distinctive and attractive appearance and which—because of the nature of the agglomerate colored speckles—are non-staining to fabric in use. U.S. Pat. No. 4,671,886 discloses mixing finely divided pigments which form large visible agglomerates with a non-agglomerating granular diluent. This is said to prevent or reduce the formation of visible agglomerates of pigment and prevent staining problems. The premix is used to color granular products such as spray dried granules. However, in all the prior art relating to coloured particles, the issue of fabric staining is so sensitive that particles containing dyes or pigments always do so at low levels to avoid localized high concentrations of colouring materials. For example, U.S. Pat. No. 3,931,037 describes granular detergent product substantially uncolored in its dry state which contains coloring materials. These particles are said not to be subject to separation and segregation and to be readily soluble or dispersible when the detergent is mixed with water to form a colored washing solution.
The present inventors have found that hueing agents such as pigments and/or dyes may be incorporated into detergent particles without causing staining of items to be washed when incorporated in a detergent composition. The particles according to the invention can incorporate relatively high levels of dye and/or pigment and enable use of such particles in detergent compositions at relatively high levels without causing fabric staining or spotting. The present inventors have now found that by incorporating a suspending agent for the hueing agent in the coloured particles, the problems of the prior art are alleviated. Without wishing to be bound by theory the inventors believe that this is because on contact of the detergent composition with water, the coloured particles rapidly dissolve/disintegrate. However, the deposition of the hueing agent is slowed by the suspending agent until concentrated regions of hueing agent are dispersed and this ensures that spotting of the hueing agent, or staining on the fabrics being laundered is substantially avoided.